The present invention relates to a touch sensor panel controller and a semiconductor device using the same, and a technique useful in application to e.g. an LC display panel unit with a touch sensor panel unit incorporated therein.
For example, a touch sensor panel supporting multiple points of touching according to a mutual capacitance method has Y electrodes used as drive electrodes and X electrodes used as detection electrodes, in which the X and Y electrodes are crossing each other at right angles with dielectric interposed therebetween, and capacitance (i.e. intersection capacitance) is formed at each intersection. In case that a finger or hand produces a capacitance near the intersection capacitance, the mutual capacitance at a node concerned is reduced by a combined capacitance produced by the finger or hand. To detect which intersection capacitance the change in the mutual capacitance comes from, the touch sensor panel controller activates the drive electrodes by a pulse to perform a charging operation by the pulse in turn, repeats the operation for detecting a change of the stored charge from the respective detection electrodes in turn, and takes a signal depending on a change of the mutual capacitance of intersection capacitances arranged in a matrix form. A controller for which a mutual capacitance method like this is adopted, and which activates a touch sensor panel to detect signals has been described by e.g. U.S. Patent Application Ser. No. 2007/0257890A1. In the above patent document, the detection circuit for detecting signals from the X electrodes includes an integration circuit with an operational amplifier incorporated therein. In the integration circuit, an electric charge, which is defined by the product of a drive voltage of the Y electrodes and a capacitance value of the intersection capacitance, is accumulated according to AC pulse driving in turn. The coordinates of points in a location which the finger or hand has approached are found based on the difference of accumulated charge between the case of approach of a finger or hand reducing the capacitance value of the intersection capacitance, and the case of approach of a finger or hand causing no change, etc.